I. Field of the Invention
The present invention relates to a fastening device for plates, in particular for plates of glass substrate, comprising retaining elements placed between each substrate and a supporting structure for the purpose of transferring the loads of the substrates to the supporting structure, which retaining elements comprise means for limiting the dimensional variations or differences, the deformations and the movements between the substrates and the supporting structure.
II. Description of Related Art
During the production of glass facades for tertiary buildings or buildings for domestic purposes, many techniques are known that use isolated retaining or fastening elements that support the glazing units, for example in a facade revetment, only over a small surface area, that make it possible to produce largely transparent constructions.
Thus, there exist, for example, systems that support the substrates in pairs at their peripheral joint bead that separates them or at the retaining elements that pass through drill holes made in the substrates.
For the safety of glass facades, various loads are of importance. On the one hand, there are the external loads (weight of the glass itself, wind, precipitation, impacts, etc.), and, on the other hand, those that result from actions via stresses following, for example, temperature variations, tolerances in the supporting structure and assembly errors, for example.
In addition, it is known that a glass substrate is fragile and, unlike ductile materials (metals or plastics, for example), supports only elastic deformations and no plastic deformation.
In principle, the glass substrate must therefore be subjected to minimal mechanical strains during the transfer of loads exerted by the latter on the supporting structure.
Thus, when mechanically strong facades need to be designed, these facades being obtained by the juxtaposition of a plurality of glass substrates, the designer has several solutions:                a first solution consists in overdimensioning the glass substrates, this overdimensioning usually being achieved in the thickness of the substrate. The main disadvantage of this solution lies in the fact that it leads to an increase in the weights, which assuredly involves an overdimensioning of the retaining elements and a reinforcement of the supporting structure.        a second solution consists not in overdimensioning the glass substrates but in accepting between them and the supporting structure retaining elements that incorporate degrees of freedom (in translation, in rotation, combination of the two) making it possible to induce movements between the substrates and the supporting structure without placing the substrates under stress.        
This second solution gives full satisfaction as long as it is appropriate to compensate for the dimensional tolerances between the substrates or to transmit forces originating from external loads (wind for example) to the supporting structure, but it does not work when it is necessary to withstand forces resulting from temperature variation of the gaseous fluid trapped between the two substrates. Specifically, any temperature variation in a direction of an increase or decrease in temperature induces variations in the volume or pressure of the trapped fluid and generates phenomena of swelling or, on the contrary, phenomena of contraction between the substrates that may cause stresses on the substrates that exceed the acceptable mechanical limits thereby risking causing breakages.